<!DOCTYPE html>
<html>

<head>
    <title>Example</title>
    <style type="text/css">
        /* ID选择器--对应全局id属性*/
        #w3canchor {
            border: thin black solid;
            padding: 4px;
        }
    </style>
</head>

<body>
    <a class="class1 class2" href="http://apress.com">Visit the Apress website</a>
    <p>I like <span class="class2">apples</span> and oranges.</p>
    <a id="w3canchor" href="http://w3c.org">Visit the W3C website</a>
</body>

</html>